Human endothelial nitric oxide synthase / eNOS / NOS3

evidence_span

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experimental_model

Human umbilical vein and bovine aortic endothelial cells in an in vitro ischaemia-reperfusion model

exposure

Hyperbaric oxygen after combined hypoxia and hypoglycaemia; L-NAME

limitations

An in vitro model requiring both hypoxia and hypoglycaemia to induce the adhesion molecule. The nitric oxide synthase inhibitor arm supports the proposed route.

nutrient_topic

Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. · Hyperbaric oxygen therapy

organism

Human and bovine cells

plain_language

The effect runs through the nitric oxide enzyme the vessel wall makes.

primary_references

[hbot-p10666024] Hyperbaric oxygen downregulates ICAM-1 expression induced by hypoxia and hypoglycemia: the role of NOS. (2000). https://pubmed.ncbi.nlm.nih.gov/10666024/ DOI: 10.1152/ajpcell.2000.278.2.c292

tissue_or_cell_type

Vascular endothelium

Hyperbaric oxygen: the exposure, its reactive species, the signals they carry, and the nutrient-dependent enzymes that handle them (2026-09-19) · lines 738–749

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human umbilical vein and bovine aortic endothelial cells in an in vitro ischaemia-reperfusion model · source_derived_draft · unverified_draft

### hbot-enos-mediates-icam Exposure induced endothelial nitric oxide synthase synthesis, and the inhibitor L-NAME attenuated the inhibition of ICAM-1 expression. Condition category: normal nutrient_topic: Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. plain_language: The effect runs through the nitric oxide enzyme the vessel wall makes. organism: Human and bovine cells tissue_or_cell_type: Vascular endothelium experimental_model: Human umbilical vein and bovine aortic endothelial cells in an in vitro ischaemia-reperfusion model limitations: An in vitro model requiring both hypoxia and hypoglycaemia to induce the adhesion molecule. The nitric oxide synthase inhibitor arm supports the proposed route. exposure: Hyperbaric oxygen after combined hypoxia and hypoglycaemia; L-NAME evidence_span: {"source_cache": "artifacts/hbot-research/10666024.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "9bb8781cab37af1af9f292e4611c19f273de986e86be681a357058d2cfb87ad8", "start_char": 0, "end_char": 1182, "text_sha256": "9bb8781cab37af1af9f292e4611c19f273de986e86be681a357058d2cfb87ad8"} [hbot-p10666024] Hyperbaric oxygen downregulates ICAM-1 expression induced by hypoxia and hypoglycemia: the role of NOS. (2000). https://pubmed.ncbi.nlm.nih.gov/10666024/ DOI: 10.1152/ajpcell.2000.278.2.c292

evidence_span

{"source_cache": "artifacts/citrulline-research/10608822.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd", "start_char": 0, "end_char": 2100, "text_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd"}

experimental_model

Purified recombinant enzyme activity and cofactor analysis

exposure

Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements

limitations

Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people.

nutrient_topic

Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline

organism

Human NOS3 expressed in yeast

plain_language

Citrulline is also produced when the nitric-oxide pathway uses arginine.

primary_references

[citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658

tissue_or_cell_type

Endothelial NOS enzyme preparation

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 502–513

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant enzyme activity and cofactor analysis · source_derived_draft · unverified_draft

### citrulline-nos-citrulline Purified human eNOS converted arginine in an assay measuring citrulline formation, with an arginine Km of 3.9 micromolar. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: Citrulline is also produced when the nitric-oxide pathway uses arginine. organism: Human NOS3 expressed in yeast tissue_or_cell_type: Endothelial NOS enzyme preparation experimental_model: Purified recombinant enzyme activity and cofactor analysis limitations: Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people. exposure: Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements evidence_span: {"source_cache": "artifacts/citrulline-research/10608822.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd", "start_char": 0, "end_char": 2100, "text_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd"} [citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658

evidence_span

{"source_cache": "artifacts/citrulline-research/1378832.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "265be186f6d8172b272e7b1e75b4fbae12a6df78c7396cad499bce2b195b1206", "start_char": 0, "end_char": 1652, "text_sha256": "265be186f6d8172b272e7b1e75b4fbae12a6df78c7396cad499bce2b195b1206"}

experimental_model

Functional expression and reporter-cell coculture

exposure

NOS3 transfection and calcium ionophore A23187

limitations

Heterologous expression; reporter activation supports bioactive NO production, not a clinical calcium supplementation effect.

nutrient_topic

Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline

organism

Human NOS3 expressed in NIH3T3 cells; rat reporter fibroblasts

plain_language

Arginine feeds an enzyme that makes the signal NO while also producing citrulline.

primary_references

[citrulline-p1378832] Cloning and expression of a cDNA encoding human endothelium-derived relaxing factor/nitric oxide synthase. (1992). https://pubmed.ncbi.nlm.nih.gov/1378832/ DOI: 10.1016/s0021-9258(18)42066-2

tissue_or_cell_type

Arginine conversion and NO-dependent reporter guanylate cyclase activity

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 463–474

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Functional expression and reporter-cell coculture · source_derived_draft · unverified_draft

### citrulline-nos-no Cells expressing human endothelial NOS produced bioactive NO that increased guanylate cyclase activity in cocultured reporter cells. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: Arginine feeds an enzyme that makes the signal NO while also producing citrulline. organism: Human NOS3 expressed in NIH3T3 cells; rat reporter fibroblasts tissue_or_cell_type: Arginine conversion and NO-dependent reporter guanylate cyclase activity experimental_model: Functional expression and reporter-cell coculture limitations: Heterologous expression; reporter activation supports bioactive NO production, not a clinical calcium supplementation effect. exposure: NOS3 transfection and calcium ionophore A23187 evidence_span: {"source_cache": "artifacts/citrulline-research/1378832.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "265be186f6d8172b272e7b1e75b4fbae12a6df78c7396cad499bce2b195b1206", "start_char": 0, "end_char": 1652, "text_sha256": "265be186f6d8172b272e7b1e75b4fbae12a6df78c7396cad499bce2b195b1206"} [citrulline-p1378832] Cloning and expression of a cDNA encoding human endothelium-derived relaxing factor/nitric oxide synthase. (1992). https://pubmed.ncbi.nlm.nih.gov/1378832/ DOI: 10.1016/s0021-9258(18)42066-2

duration

Not stated here

evidence_access

Primary PubMed abstract and indexed metadata reviewed. Full-text method details not stated here remain unresolved.

experimental_model

Human endothelial cells

exposure

Geranylgeranyl diphosphate 1 to 10 micromolar, farnesyl diphosphate 5 to 10 micromolar, L-mevalonate 200 micromolar or LDL 1 mg/ml added with mevastatin

limitations

This identifies which isoprenoid carries the effect; it does not establish that geranylgeranyl diphosphate is limiting at ordinary statin doses in a person.

organism

Human endothelial cells

plain_language

Geranylgeranyl diphosphate reversed the statin-induced rise in endothelial nitric oxide synthase, while farnesyl diphosphate and low-density lipoprotein did not.

primary_references

Post-transcriptional regulation of endothelial nitric oxide synthase mRNA stability by Rho GTPase. (1998). https://pubmed.ncbi.nlm.nih.gov/9727051/ DOI: 10.1074/jbc.273.37.24266

route

In vitro

tissue

Endothelial nitric oxide synthase expression and Rho membrane translocation

Atorvastatin: mechanism of action from target occupancy to isoprenoids, transport, muscle and metabolism (2026-09-22) · lines 67–76

Original AI-assisted curation of twelve primary studies resolved by PubMed title search and cross-checked against live PubMed metadata. Findings obtained with mevastatin, simvastatin or the statin class are recorded against those subjects. Study-specific citations, doses, negative findings and limitations retained. Not publisher full text. · supports · · source_derived_draft · unverified_draft

## ggpp-reverses-the-nos-response Geranylgeranyl diphosphate reversed the statin-induced rise in endothelial nitric oxide synthase, while farnesyl diphosphate and low-density lipoprotein did not. Model/species: Human endothelial cells Tissue/system: Endothelial nitric oxide synthase expression and Rho membrane translocation Exposure: Geranylgeranyl diphosphate 1 to 10 micromolar, farnesyl diphosphate 5 to 10 micromolar, L-mevalonate 200 micromolar or LDL 1 mg/ml added with mevastatin Route: In vitro Duration: Not stated here Limits: This identifies which isoprenoid carries the effect; it does not establish that geranylgeranyl diphosphate is limiting at ordinary statin doses in a person. Primary reference: Post-transcriptional regulation of endothelial nitric oxide synthase mRNA stability by Rho GTPase. (1998). https://pubmed.ncbi.nlm.nih.gov/9727051/ DOI: 10.1074/jbc.273.37.24266 Access: Primary PubMed abstract and indexed metadata reviewed. Full-text method details not stated here remain unresolved.

duration

Not stated here

evidence_access

Primary PubMed abstract and indexed metadata reviewed. Full-text method details not stated here remain unresolved.

experimental_model

Human endothelial cells

exposure

Mevastatin 1 to 10 micromolar

limitations

The statin tested was mevastatin, not atorvastatin, and this is an expression change in cultured cells rather than a vascular outcome.

organism

Human endothelial cells

plain_language

Mevastatin increased endothelial nitric oxide synthase messenger RNA by about 305 percent and protein by about 180 percent in human endothelial cells.

primary_references

Post-transcriptional regulation of endothelial nitric oxide synthase mRNA stability by Rho GTPase. (1998). https://pubmed.ncbi.nlm.nih.gov/9727051/ DOI: 10.1074/jbc.273.37.24266

route

In vitro

tissue

Endothelial nitric oxide synthase expression

Atorvastatin: mechanism of action from target occupancy to isoprenoids, transport, muscle and metabolism (2026-09-22) · lines 56–65

Original AI-assisted curation of twelve primary studies resolved by PubMed title search and cross-checked against live PubMed metadata. Findings obtained with mevastatin, simvastatin or the statin class are recorded against those subjects. Study-specific citations, doses, negative findings and limitations retained. Not publisher full text. · supports · · source_derived_draft · unverified_draft

## statin-raises-endothelial-nos Mevastatin increased endothelial nitric oxide synthase messenger RNA by about 305 percent and protein by about 180 percent in human endothelial cells. Model/species: Human endothelial cells Tissue/system: Endothelial nitric oxide synthase expression Exposure: Mevastatin 1 to 10 micromolar Route: In vitro Duration: Not stated here Limits: The statin tested was mevastatin, not atorvastatin, and this is an expression change in cultured cells rather than a vascular outcome. Primary reference: Post-transcriptional regulation of endothelial nitric oxide synthase mRNA stability by Rho GTPase. (1998). https://pubmed.ncbi.nlm.nih.gov/9727051/ DOI: 10.1074/jbc.273.37.24266 Access: Primary PubMed abstract and indexed metadata reviewed. Full-text method details not stated here remain unresolved.

evidence_access

Primary full text

experimental_model

Human HUVECs, 0.5 mM silicon preparation.

limitations

Expression is not measured catalytic flux or proof that silicon replaces established metal cofactors.

nutrient_topic

Silica collection; molecular form, preparation, species, exposure and manipulation remain explicit. · Silica and soluble silicon

plain_language

An individual antioxidant or vascular enzyme was measured.

primary_references

Ionic silicon improves endothelial cells' survival under toxic oxidative stress by overexpressing angiogenic markers and antioxidant enzymes. · 2018 · https://pubmed.ncbi.nlm.nih.gov/30062712/ · DOI 10.1002/term.2744

Silica: soluble silicon, cellular transport and particle-specific mechanisms (2026-09-19) · lines 312–318

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human HUVECs, 0.5 mM silicon preparation. · source_derived_draft · unverified_draft

## silica-endothelial-nos3 An individual antioxidant or vascular enzyme was measured. Silicon-treated HUVECs increased NOS3 mRNA under the reported normal and peroxide conditions. Model: Human HUVECs, 0.5 mM silicon preparation. Limitations: Expression is not measured catalytic flux or proof that silicon replaces established metal cofactors. Evidence access: Primary full text Ionic silicon improves endothelial cells' survival under toxic oxidative stress by overexpressing angiogenic markers and antioxidant enzymes. · 2018 · https://pubmed.ncbi.nlm.nih.gov/30062712/ · DOI 10.1002/term.2744

evidence_span

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experimental_model

Purified recombinant enzyme activity and cofactor analysis

exposure

Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements

limitations

Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people.

nutrient_topic

Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline

organism

Human NOS3 expressed in yeast

plain_language

One vitamin-B2-derived flavin is part of the enzyme.

primary_references

[citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658

tissue_or_cell_type

Endothelial NOS enzyme preparation

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 528–539

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant enzyme activity and cofactor analysis · source_derived_draft · unverified_draft

### citrulline-nos-fad The purified human eNOS preparation contained approximately 0.56 FAD equivalents per subunit. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: One vitamin-B2-derived flavin is part of the enzyme. organism: Human NOS3 expressed in yeast tissue_or_cell_type: Endothelial NOS enzyme preparation experimental_model: Purified recombinant enzyme activity and cofactor analysis limitations: Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people. exposure: Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements evidence_span: {"source_cache": "artifacts/citrulline-research/10608822.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd", "start_char": 0, "end_char": 2100, "text_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd"} [citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658

evidence_span

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experimental_model

Purified recombinant enzyme activity and cofactor analysis

exposure

Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements

limitations

Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people.

nutrient_topic

Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline

organism

Human NOS3 expressed in yeast

plain_language

A second B2-derived flavin participates in the enzyme system.

primary_references

[citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658

tissue_or_cell_type

Endothelial NOS enzyme preparation

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 541–552

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant enzyme activity and cofactor analysis · source_derived_draft · unverified_draft

### citrulline-nos-fmn The human eNOS preparation contained approximately 0.79 FMN equivalents per subunit. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: A second B2-derived flavin participates in the enzyme system. organism: Human NOS3 expressed in yeast tissue_or_cell_type: Endothelial NOS enzyme preparation experimental_model: Purified recombinant enzyme activity and cofactor analysis limitations: Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people. exposure: Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements evidence_span: {"source_cache": "artifacts/citrulline-research/10608822.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd", "start_char": 0, "end_char": 2100, "text_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd"} [citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658

evidence_span

{"source_cache": "artifacts/citrulline-research/10608822.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd", "start_char": 0, "end_char": 2100, "text_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd"}

experimental_model

Purified recombinant enzyme activity and cofactor analysis

exposure

Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements

limitations

Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people.

nutrient_topic

Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline

organism

Human NOS3 expressed in yeast

plain_language

The nitric-oxide machinery includes an iron-containing heme group.

primary_references

[citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658

tissue_or_cell_type

Endothelial NOS enzyme preparation

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 554–565

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant enzyme activity and cofactor analysis · source_derived_draft · unverified_draft

### citrulline-nos-heme Heme and protein-bound iron were detected in purified human eNOS by independent analytical methods. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: The nitric-oxide machinery includes an iron-containing heme group. organism: Human NOS3 expressed in yeast tissue_or_cell_type: Endothelial NOS enzyme preparation experimental_model: Purified recombinant enzyme activity and cofactor analysis limitations: Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people. exposure: Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements evidence_span: {"source_cache": "artifacts/citrulline-research/10608822.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd", "start_char": 0, "end_char": 2100, "text_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd"} [citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658

evidence_span

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experimental_model

Purified recombinant enzyme activity and cofactor analysis

exposure

Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements

limitations

Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people.

nutrient_topic

Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline

organism

Human NOS3 expressed in yeast

plain_language

Zinc is a structural component measured in the enzyme, not an automatic reason for high-dose zinc.

primary_references

[citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658

tissue_or_cell_type

Endothelial NOS enzyme preparation

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 567–578

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant enzyme activity and cofactor analysis · source_derived_draft · unverified_draft

### citrulline-nos-zinc Metal analysis detected approximately 0.43 zinc equivalents per human eNOS subunit. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: Zinc is a structural component measured in the enzyme, not an automatic reason for high-dose zinc. organism: Human NOS3 expressed in yeast tissue_or_cell_type: Endothelial NOS enzyme preparation experimental_model: Purified recombinant enzyme activity and cofactor analysis limitations: Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people. exposure: Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements evidence_span: {"source_cache": "artifacts/citrulline-research/10608822.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd", "start_char": 0, "end_char": 2100, "text_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd"} [citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658

availability_state

biomarker_context Imported condition classification; unverified.

evidence_span

{"source_cache": "artifacts/sildenafil-research/9628657.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "71870b989514f322eb55b17364921cc67de92b3deef59bdf75e2c35db6a97ff7", "start_char": 0, "end_char": 1781, "text_sha256": "71870b989514f322eb55b17364921cc67de92b3deef59bdf75e2c35db6a97ff7"}

experimental_model

Pentobarbital-anaesthetised dogs with pelvic nerve stimulation and nitric oxide synthase inhibition

exposure

Intravenous sildenafil 1 to 100 micrograms per kilogram, with N-omega-nitro-L-arginine

limitations

An in vivo test of the amplifier principle with the nitric oxide synthase inhibitor as the control. Anaesthetised animals.

nutrient_topic

Sildenafil research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from its N-desmethyl metabolite and its target enzyme from the homologous retinal PDE6. · Sildenafil

organism

Dog

plain_language

In the living animal it raised nothing by itself and roughly doubled what the nerve was already doing.

primary_references

[sil-p9628657] Effect of the selective phosphodiesterase type 5 inhibitor sildenafil on erectile dysfunction in the anesthetized dog. (1998). https://pubmed.ncbi.nlm.nih.gov/9628657/ DOI: 10.1016/s0022-5347(01)63097-0

tissue_or_cell_type

Corpus cavernosum and systemic circulation

trigger_kind

biomarker_context Imported condition classification; unverified.

Sildenafil: the enzyme it occupies instead of the substrate, why it cannot start a signal it can only preserve, the organic nitrate interaction that follows from that, the homologous retinal enzyme ten-fold away, and the pulmonary circulation where the same mechanism became a second indication (2026-09-22) · lines 301–312

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Pentobarbital-anaesthetised dogs with pelvic nerve stimulation and nitric oxide synthase inhibition · source_derived_draft · unverified_draft

### sil-potentiates-only-the-nerve-signal The effects of pelvic nerve stimulation on intracavernosal pressure and penile blood flow were blocked by N-omega-nitro-L-arginine in a dose-related manner confirming the role of nitric oxide, and intravenous sildenafil at 1 to 100 micrograms per kilogram had no direct effect on intracavernosal pressure but potentiated the increase induced by nerve stimulation at plasma concentrations consistent with its relaxation effect on isolated human cavernosal tissue and its inhibition of the enzyme in vitro, with no significant effect on blood pressure or heart rate. Condition category: biomarker_context nutrient_topic: Sildenafil research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from its N-desmethyl metabolite and its target enzyme from the homologous retinal PDE6. plain_language: In the living animal it raised nothing by itself and roughly doubled what the nerve was already doing. organism: Dog tissue_or_cell_type: Corpus cavernosum and systemic circulation experimental_model: Pentobarbital-anaesthetised dogs with pelvic nerve stimulation and nitric oxide synthase inhibition limitations: An in vivo test of the amplifier principle with the nitric oxide synthase inhibitor as the control. Anaesthetised animals. exposure: Intravenous sildenafil 1 to 100 micrograms per kilogram, with N-omega-nitro-L-arginine evidence_span: {"source_cache": "artifacts/sildenafil-research/9628657.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "71870b989514f322eb55b17364921cc67de92b3deef59bdf75e2c35db6a97ff7", "start_char": 0, "end_char": 1781, "text_sha256": "71870b989514f322eb55b17364921cc67de92b3deef59bdf75e2c35db6a97ff7"} [sil-p9628657] Effect of the selective phosphodiesterase type 5 inhibitor sildenafil on erectile dysfunction in the anesthetized dog. (1998). https://pubmed.ncbi.nlm.nih.gov/9628657/ DOI: 10.1016/s0022-5347(01)63097-0

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_span

{"source_cache": "artifacts/sildenafil-research/11468204.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "41d880663288811422c4400d86de1eedd4d5b254d8bb3a59a8fbff01dedbcb24", "start_char": 0, "end_char": 1820, "text_sha256": "41d880663288811422c4400d86de1eedd4d5b254d8bb3a59a8fbff01dedbcb24"}

experimental_model

Randomised double-blind hypoxic challenge in ten volunteers with right heart catheterisation, plus isolated perfused lung and chronic hypoxia in wild-type and endothelial nitric oxide synthase deficient mice

exposure

Sildenafil 100 milligrams orally before 11 percent oxygen for 30 minutes, and 25 milligrams per kilogram daily through three weeks of 10 percent oxygen in mice

limitations

The knockout arm is what makes this decisive about the source of cyclic GMP, and the human arm measures pressure invasively. Ten volunteers, and the mouse exposure is far longer than the human one.

nutrient_topic

Sildenafil research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from its N-desmethyl metabolite and its target enzyme from the homologous retinal PDE6. · Sildenafil

organism

Mouse

plain_language

It still works when the main source of the upstream signal has been deleted, so something else is supplying the messenger.

primary_references

[sil-p11468204] Sildenafil inhibits hypoxia-induced pulmonary hypertension. (2001). https://pubmed.ncbi.nlm.nih.gov/11468204/ DOI: 10.1161/hc2901.093117

tissue_or_cell_type

Pulmonary circulation

trigger_kind

machinery_impairment Imported condition classification; unverified.

Sildenafil: the enzyme it occupies instead of the substrate, why it cannot start a signal it can only preserve, the organic nitrate interaction that follows from that, the homologous retinal enzyme ten-fold away, and the pulmonary circulation where the same mechanism became a second indication (2026-09-22) · lines 509–520

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Randomised double-blind hypoxic challenge in ten volunteers with right heart catheterisation, plus isolated perfused lung and chronic hypoxia in wild-type and endothelial nitric oxide synthase deficient mice · source_derived_draft · unverified_draft

### sil-works-without-enos In isolated perfused lung of wild-type and endothelial nitric oxide synthase deficient mice sildenafil markedly blunted acute hypoxic pulmonary vasoconstriction, wild-type mice dosed through three weeks of hypoxia showed a significant reduction in right ventricular systolic pressure from 43.3 to 29.9 millimetres of mercury coupled with a small reduction in right ventricular hypertrophy and inhibition of pulmonary vascular remodelling, while in the knockout mice the drug attenuated the rise in right ventricular systolic pressure but without significant effect on hypertrophy or remodelling, so the endothelial pathway contributes but other biochemical sources of cyclic GMP also play a role. Condition category: machinery_impairment nutrient_topic: Sildenafil research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from its N-desmethyl metabolite and its target enzyme from the homologous retinal PDE6. plain_language: It still works when the main source of the upstream signal has been deleted, so something else is supplying the messenger. organism: Mouse tissue_or_cell_type: Pulmonary circulation experimental_model: Randomised double-blind hypoxic challenge in ten volunteers with right heart catheterisation, plus isolated perfused lung and chronic hypoxia in wild-type and endothelial nitric oxide synthase deficient mice limitations: The knockout arm is what makes this decisive about the source of cyclic GMP, and the human arm measures pressure invasively. Ten volunteers, and the mouse exposure is far longer than the human one. exposure: Sildenafil 100 milligrams orally before 11 percent oxygen for 30 minutes, and 25 milligrams per kilogram daily through three weeks of 10 percent oxygen in mice evidence_span: {"source_cache": "artifacts/sildenafil-research/11468204.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "41d880663288811422c4400d86de1eedd4d5b254d8bb3a59a8fbff01dedbcb24", "start_char": 0, "end_char": 1820, "text_sha256": "41d880663288811422c4400d86de1eedd4d5b254d8bb3a59a8fbff01dedbcb24"} [sil-p11468204] Sildenafil inhibits hypoxia-induced pulmonary hypertension. (2001). https://pubmed.ncbi.nlm.nih.gov/11468204/ DOI: 10.1161/hc2901.093117

evidence_span

{"source_cache": "artifacts/hbot-research/31035003.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "e0b19a857412f1a255ecc82052eb403389bcf5596a562828c04558e1d4354efc", "start_char": 0, "end_char": 1966, "text_sha256": "e0b19a857412f1a255ecc82052eb403389bcf5596a562828c04558e1d4354efc"}

experimental_model

Randomised comparison of 32 patients receiving standard wound care with or without hyperbaric oxygen, with ulcer tissue biopsies

exposure

Hyperbaric oxygen with standard wound care for 20 days

limitations

A small randomised human study with tissue-level molecular endpoints. Correlations between Nrf2 and growth factors are associations within treated tissue.

nutrient_topic

Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. · Hyperbaric oxygen therapy

organism

Human

plain_language

The same nitric oxide enzyme appears again, this time in the wound, with the immune cells joining in.

primary_references

[hbot-p31035003] Tissue-specific role of Nrf2 in the treatment of diabetic foot ulcers during hyperbaric oxygen therapy. (2019). https://pubmed.ncbi.nlm.nih.gov/31035003/ DOI: 10.1016/j.freeradbiomed.2019.04.031

tissue_or_cell_type

Diabetic foot ulcer tissue

Hyperbaric oxygen: the exposure, its reactive species, the signals they carry, and the nutrient-dependent enzymes that handle them (2026-09-19) · lines 842–853

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Randomised comparison of 32 patients receiving standard wound care with or without hyperbaric oxygen, with ulcer tissue biopsies · source_derived_draft · unverified_draft

### hbot-enos-nitrite-wound Expression of endothelial nitric oxide synthase and nitrite concentrations were significantly increased in treated subjects, and treatment sensitised macrophages to release FGF-2 and EGF while increasing the neutrophil attractant CXCL-8 and thereby the release of CCL2. Condition category: normal nutrient_topic: Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. plain_language: The same nitric oxide enzyme appears again, this time in the wound, with the immune cells joining in. organism: Human tissue_or_cell_type: Diabetic foot ulcer tissue experimental_model: Randomised comparison of 32 patients receiving standard wound care with or without hyperbaric oxygen, with ulcer tissue biopsies limitations: A small randomised human study with tissue-level molecular endpoints. Correlations between Nrf2 and growth factors are associations within treated tissue. exposure: Hyperbaric oxygen with standard wound care for 20 days evidence_span: {"source_cache": "artifacts/hbot-research/31035003.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "e0b19a857412f1a255ecc82052eb403389bcf5596a562828c04558e1d4354efc", "start_char": 0, "end_char": 1966, "text_sha256": "e0b19a857412f1a255ecc82052eb403389bcf5596a562828c04558e1d4354efc"} [hbot-p31035003] Tissue-specific role of Nrf2 in the treatment of diabetic foot ulcers during hyperbaric oxygen therapy. (2019). https://pubmed.ncbi.nlm.nih.gov/31035003/ DOI: 10.1016/j.freeradbiomed.2019.04.031

evidence_span

{"source_cache": "artifacts/hbot-research/10749833.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1470d09e77b6d6f6af3131a6f7db2cca647dde3655662a1c83f9d5d375f1c687", "start_char": 0, "end_char": 1283, "text_sha256": "1470d09e77b6d6f6af3131a6f7db2cca647dde3655662a1c83f9d5d375f1c687"}

experimental_model

Regional cerebral blood flow and electroencephalography in anaesthetised rats

exposure

Oxygen at 1, 3, 4 and 5 ATA with L-NAME, L-arginine, nitric oxide donors or MK-801

limitations

A time-course study at toxic pressures. It shows the nitric oxide effect reverses with exposure time, which a single time point would miss.

nutrient_topic

Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. · Hyperbaric oxygen therapy

organism

Rat

plain_language

Early on there is too little of this molecule, later too much.

primary_references

[hbot-p10749833] Nitric oxide and cerebral blood flow responses to hyperbaric oxygen. (2000). https://pubmed.ncbi.nlm.nih.gov/10749833/ DOI: 10.1152/jappl.2000.88.4.1381

tissue_or_cell_type

Brain

Hyperbaric oxygen: the exposure, its reactive species, the signals they carry, and the nutrient-dependent enzymes that handle them (2026-09-19) · lines 205–216

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Regional cerebral blood flow and electroencephalography in anaesthetised rats · source_derived_draft · unverified_draft

### hbot-no-production-rises-late A relative lack of nitric oxide activity contributed to the early decrease in blood flow, but as exposure was prolonged nitric oxide production increased and augmented blood flow in anticipation of neuronal excitation. Condition category: normal nutrient_topic: Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. plain_language: Early on there is too little of this molecule, later too much. organism: Rat tissue_or_cell_type: Brain experimental_model: Regional cerebral blood flow and electroencephalography in anaesthetised rats limitations: A time-course study at toxic pressures. It shows the nitric oxide effect reverses with exposure time, which a single time point would miss. exposure: Oxygen at 1, 3, 4 and 5 ATA with L-NAME, L-arginine, nitric oxide donors or MK-801 evidence_span: {"source_cache": "artifacts/hbot-research/10749833.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1470d09e77b6d6f6af3131a6f7db2cca647dde3655662a1c83f9d5d375f1c687", "start_char": 0, "end_char": 1283, "text_sha256": "1470d09e77b6d6f6af3131a6f7db2cca647dde3655662a1c83f9d5d375f1c687"} [hbot-p10749833] Nitric oxide and cerebral blood flow responses to hyperbaric oxygen. (2000). https://pubmed.ncbi.nlm.nih.gov/10749833/ DOI: 10.1152/jappl.2000.88.4.1381

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_span

{"source_cache": "artifacts/hbot-research/16299259.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "76c0554557a30ac9a32f25b74b27edb5f8f8a57ee0c0660dfe5619b78732c730", "start_char": 0, "end_char": 1502, "text_sha256": "76c0554557a30ac9a32f25b74b27edb5f8f8a57ee0c0660dfe5619b78732c730"}

experimental_model

Human volunteers, mice, and endothelial nitric oxide synthase knockout mice

exposure

2.0 atmospheres absolute oxygen for 2 hours, single and over 20 treatments

limitations

The knockout and inhibitor arms carry the causal claim. Progenitor phenotype is defined by surface markers and colony formation, not by a demonstrated contribution to a healed vessel.

nutrient_topic

Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. · Hyperbaric oxygen therapy

organism

Human and mouse

plain_language

Remove the enzyme that makes nitric oxide and the cells stay in the marrow.

primary_references

[hbot-p16299259] Stem cell mobilization by hyperbaric oxygen. (2006). https://pubmed.ncbi.nlm.nih.gov/16299259/ DOI: 10.1152/ajpheart.00888.2005

tissue_or_cell_type

Bone marrow and peripheral blood

trigger_kind

machinery_impairment Imported condition classification; unverified.

Hyperbaric oxygen: the exposure, its reactive species, the signals they carry, and the nutrient-dependent enzymes that handle them (2026-09-19) · lines 569–580

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human volunteers, mice, and endothelial nitric oxide synthase knockout mice · source_derived_draft · unverified_draft

### hbot-nos3-required Stem cell mobilisation did not occur in knockout mice lacking genes for endothelial nitric oxide synthase, and pretreatment of wild-type mice with a nitric oxide synthase inhibitor prevented the elevation in stem cell factor and circulating stem cells. Condition category: machinery_impairment nutrient_topic: Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. plain_language: Remove the enzyme that makes nitric oxide and the cells stay in the marrow. organism: Human and mouse tissue_or_cell_type: Bone marrow and peripheral blood experimental_model: Human volunteers, mice, and endothelial nitric oxide synthase knockout mice limitations: The knockout and inhibitor arms carry the causal claim. Progenitor phenotype is defined by surface markers and colony formation, not by a demonstrated contribution to a healed vessel. exposure: 2.0 atmospheres absolute oxygen for 2 hours, single and over 20 treatments evidence_span: {"source_cache": "artifacts/hbot-research/16299259.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "76c0554557a30ac9a32f25b74b27edb5f8f8a57ee0c0660dfe5619b78732c730", "start_char": 0, "end_char": 1502, "text_sha256": "76c0554557a30ac9a32f25b74b27edb5f8f8a57ee0c0660dfe5619b78732c730"} [hbot-p16299259] Stem cell mobilization by hyperbaric oxygen. (2006). https://pubmed.ncbi.nlm.nih.gov/16299259/ DOI: 10.1152/ajpheart.00888.2005

evidence_span

{"source_cache": "artifacts/hbot-research/21362081.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "a830ae6900d884b73f4e5eac335263db6f9d981a0f95aa45ad3e266c44800e0b", "start_char": 0, "end_char": 1077, "text_sha256": "a830ae6900d884b73f4e5eac335263db6f9d981a0f95aa45ad3e266c44800e0b"}

experimental_model

Diabetic patients undergoing hyperbaric oxygen for refractory neuropathic ulcers, with wound margin biopsies

exposure

Clinical hyperbaric oxygen therapy courses for refractory lower-extremity ulcers

limitations

Human observational measurements within a treatment course, without a randomised comparison. Protein content is measured in the mobilised cells, not in healed tissue.

nutrient_topic

Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. · Hyperbaric oxygen therapy

organism

Human

plain_language

The enzyme that releases the cells stays switched on well after the session ends.

primary_references

[hbot-p21362081] Vasculogenic stem cell mobilization and wound recruitment in diabetic patients: increased cell number and intracellular regulatory protein content associated with hyperbaric oxygen therapy. (2011). https://pubmed.ncbi.nlm.nih.gov/21362081/ DOI: 10.1111/j.1524-475x.2010.00660.x

tissue_or_cell_type

Peripheral blood, platelets and skin wound margins

Hyperbaric oxygen: the exposure, its reactive species, the signals they carry, and the nutrient-dependent enzymes that handle them (2026-09-19) · lines 608–619

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Diabetic patients undergoing hyperbaric oxygen for refractory neuropathic ulcers, with wound margin biopsies · source_derived_draft · unverified_draft

### hbot-platelet-nos Nitric oxide synthase activity was acutely increased in patients’ platelets after treatment and remained elevated for at least 20 hours. Condition category: normal nutrient_topic: Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. plain_language: The enzyme that releases the cells stays switched on well after the session ends. organism: Human tissue_or_cell_type: Peripheral blood, platelets and skin wound margins experimental_model: Diabetic patients undergoing hyperbaric oxygen for refractory neuropathic ulcers, with wound margin biopsies limitations: Human observational measurements within a treatment course, without a randomised comparison. Protein content is measured in the mobilised cells, not in healed tissue. exposure: Clinical hyperbaric oxygen therapy courses for refractory lower-extremity ulcers evidence_span: {"source_cache": "artifacts/hbot-research/21362081.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "a830ae6900d884b73f4e5eac335263db6f9d981a0f95aa45ad3e266c44800e0b", "start_char": 0, "end_char": 1077, "text_sha256": "a830ae6900d884b73f4e5eac335263db6f9d981a0f95aa45ad3e266c44800e0b"} [hbot-p21362081] Vasculogenic stem cell mobilization and wound recruitment in diabetic patients: increased cell number and intracellular regulatory protein content associated with hyperbaric oxygen therapy. (2011). https://pubmed.ncbi.nlm.nih.gov/21362081/ DOI: 10.1111/j.1524-475x.2010.00660.x

evidence_span

{"source_cache": "artifacts/citrulline-research/1378832.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "265be186f6d8172b272e7b1e75b4fbae12a6df78c7396cad499bce2b195b1206", "start_char": 0, "end_char": 1652, "text_sha256": "265be186f6d8172b272e7b1e75b4fbae12a6df78c7396cad499bce2b195b1206"}

experimental_model

Functional expression and reporter-cell coculture

exposure

NOS3 transfection and calcium ionophore A23187

limitations

Heterologous expression; reporter activation supports bioactive NO production, not a clinical calcium supplementation effect.

nutrient_topic

Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline

organism

Human NOS3 expressed in NIH3T3 cells; rat reporter fibroblasts

plain_language

Calcium signaling can activate this enzyme; this experiment did not test taking calcium tablets.

primary_references

[citrulline-p1378832] Cloning and expression of a cDNA encoding human endothelium-derived relaxing factor/nitric oxide synthase. (1992). https://pubmed.ncbi.nlm.nih.gov/1378832/ DOI: 10.1016/s0021-9258(18)42066-2

tissue_or_cell_type

Arginine conversion and NO-dependent reporter guanylate cyclase activity

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 476–487

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Functional expression and reporter-cell coculture · source_derived_draft · unverified_draft

### citrulline-calcium-nos The calcium ionophore A23187 increased arginine-to-citrulline conversion in cells expressing human endothelial NOS. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: Calcium signaling can activate this enzyme; this experiment did not test taking calcium tablets. organism: Human NOS3 expressed in NIH3T3 cells; rat reporter fibroblasts tissue_or_cell_type: Arginine conversion and NO-dependent reporter guanylate cyclase activity experimental_model: Functional expression and reporter-cell coculture limitations: Heterologous expression; reporter activation supports bioactive NO production, not a clinical calcium supplementation effect. exposure: NOS3 transfection and calcium ionophore A23187 evidence_span: {"source_cache": "artifacts/citrulline-research/1378832.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "265be186f6d8172b272e7b1e75b4fbae12a6df78c7396cad499bce2b195b1206", "start_char": 0, "end_char": 1652, "text_sha256": "265be186f6d8172b272e7b1e75b4fbae12a6df78c7396cad499bce2b195b1206"} [citrulline-p1378832] Cloning and expression of a cDNA encoding human endothelium-derived relaxing factor/nitric oxide synthase. (1992). https://pubmed.ncbi.nlm.nih.gov/1378832/ DOI: 10.1016/s0021-9258(18)42066-2

evidence_span

{"source_cache": "artifacts/citrulline-research/8951046.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "f5c5176d8e2b671f5311c529c09abe80b8661050e73c156ee2916959aa5030cb", "start_char": 0, "end_char": 1362, "text_sha256": "f5c5176d8e2b671f5311c529c09abe80b8661050e73c156ee2916959aa5030cb"}

experimental_model

Recombinant coexpression and enzyme activity comparison

exposure

Calmodulin coexpression versus adding calmodulin after expression

limitations

Expression-system result; not a test of dietary calcium or calmodulin supplementation.

nutrient_topic

Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline

organism

Human NOS3 and human calmodulin expressed in E. coli

plain_language

How the enzyme assembles with its regulatory protein mattered.

primary_references

[citrulline-p8951046] Human endothelial nitric oxide synthase: expression in Escherichia coli, coexpression with calmodulin, and characterization. (1996). https://pubmed.ncbi.nlm.nih.gov/8951046/ DOI: 10.1006/abbi.1996.0543

tissue_or_cell_type

NOS expression and catalytic function

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 593–604

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant coexpression and enzyme activity comparison · source_derived_draft · unverified_draft

### citrulline-calmodulin-nos Coexpressing human calmodulin stabilized eNOS and raised its specific activity; later calmodulin addition did not reproduce the gain. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: How the enzyme assembles with its regulatory protein mattered. organism: Human NOS3 and human calmodulin expressed in E. coli tissue_or_cell_type: NOS expression and catalytic function experimental_model: Recombinant coexpression and enzyme activity comparison limitations: Expression-system result; not a test of dietary calcium or calmodulin supplementation. exposure: Calmodulin coexpression versus adding calmodulin after expression evidence_span: {"source_cache": "artifacts/citrulline-research/8951046.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "f5c5176d8e2b671f5311c529c09abe80b8661050e73c156ee2916959aa5030cb", "start_char": 0, "end_char": 1362, "text_sha256": "f5c5176d8e2b671f5311c529c09abe80b8661050e73c156ee2916959aa5030cb"} [citrulline-p8951046] Human endothelial nitric oxide synthase: expression in Escherichia coli, coexpression with calmodulin, and characterization. (1996). https://pubmed.ncbi.nlm.nih.gov/8951046/ DOI: 10.1006/abbi.1996.0543

evidence_span

{"source_cache": "artifacts/citrulline-research/16940192.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "42c07dd0bbacfc1ff44f78d6ce69810a58946e53c76bf5d3bf8385db5278ba8b", "start_char": 0, "end_char": 1942, "text_sha256": "42c07dd0bbacfc1ff44f78d6ce69810a58946e53c76bf5d3bf8385db5278ba8b"}

experimental_model

Ex-vivo vessel exposure and randomized pre-harvest infusion

exposure

5-MTHF ex vivo 1-100 micromolar; intravenous 5-MTHF or placebo in a separate subset

limitations

Uses 5-MTHF and acute vessel endpoints; cannot be generalized to all folic-acid doses or combination supplements.

nutrient_topic

Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline

organism

Human, vessels from 117 CABG patients

plain_language

A folate form affected availability of the NO-synthase cofactor.

primary_references

[citrulline-p16940192] 5-methyltetrahydrofolate rapidly improves endothelial function and decreases superoxide production in human vessels: effects on vascular tetrahydrobiopterin availability and endothelial nitric oxide synthase coupling. (2006). https://pubmed.ncbi.nlm.nih.gov/16940192/ DOI: 10.1161/circulationaha.106.612325

tissue_or_cell_type

Saphenous veins and internal mammary arteries

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 736–747

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Ex-vivo vessel exposure and randomized pre-harvest infusion · source_derived_draft · unverified_draft

### citrulline-folate-bh4 5-MTHF increased vascular BH4 and its proportion of total biopterin in human vessel experiments. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: A folate form affected availability of the NO-synthase cofactor. organism: Human, vessels from 117 CABG patients tissue_or_cell_type: Saphenous veins and internal mammary arteries experimental_model: Ex-vivo vessel exposure and randomized pre-harvest infusion limitations: Uses 5-MTHF and acute vessel endpoints; cannot be generalized to all folic-acid doses or combination supplements. exposure: 5-MTHF ex vivo 1-100 micromolar; intravenous 5-MTHF or placebo in a separate subset evidence_span: {"source_cache": "artifacts/citrulline-research/16940192.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "42c07dd0bbacfc1ff44f78d6ce69810a58946e53c76bf5d3bf8385db5278ba8b", "start_char": 0, "end_char": 1942, "text_sha256": "42c07dd0bbacfc1ff44f78d6ce69810a58946e53c76bf5d3bf8385db5278ba8b"} [citrulline-p16940192] 5-methyltetrahydrofolate rapidly improves endothelial function and decreases superoxide production in human vessels: effects on vascular tetrahydrobiopterin availability and endothelial nitric oxide synthase coupling. (2006). https://pubmed.ncbi.nlm.nih.gov/16940192/ DOI: 10.1161/circulationaha.106.612325

evidence_span

{"source_cache": "artifacts/citrulline-research/16940192.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "42c07dd0bbacfc1ff44f78d6ce69810a58946e53c76bf5d3bf8385db5278ba8b", "start_char": 0, "end_char": 1942, "text_sha256": "42c07dd0bbacfc1ff44f78d6ce69810a58946e53c76bf5d3bf8385db5278ba8b"}

experimental_model

Ex-vivo vessel exposure and randomized pre-harvest infusion

exposure

5-MTHF ex vivo 1-100 micromolar; intravenous 5-MTHF or placebo in a separate subset

limitations

Uses 5-MTHF and acute vessel endpoints; cannot be generalized to all folic-acid doses or combination supplements.

nutrient_topic

Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline

organism

Human, vessels from 117 CABG patients

plain_language

The enzyme used its electron supply more productively under the tested conditions.

primary_references

[citrulline-p16940192] 5-methyltetrahydrofolate rapidly improves endothelial function and decreases superoxide production in human vessels: effects on vascular tetrahydrobiopterin availability and endothelial nitric oxide synthase coupling. (2006). https://pubmed.ncbi.nlm.nih.gov/16940192/ DOI: 10.1161/circulationaha.106.612325

tissue_or_cell_type

Saphenous veins and internal mammary arteries

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 749–760

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Ex-vivo vessel exposure and randomized pre-harvest infusion · source_derived_draft · unverified_draft

### citrulline-folate-coupling 5-MTHF improved eNOS coupling and increased its dimer-to-monomer ratio and activity in the human vessel study. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: The enzyme used its electron supply more productively under the tested conditions. organism: Human, vessels from 117 CABG patients tissue_or_cell_type: Saphenous veins and internal mammary arteries experimental_model: Ex-vivo vessel exposure and randomized pre-harvest infusion limitations: Uses 5-MTHF and acute vessel endpoints; cannot be generalized to all folic-acid doses or combination supplements. exposure: 5-MTHF ex vivo 1-100 micromolar; intravenous 5-MTHF or placebo in a separate subset evidence_span: {"source_cache": "artifacts/citrulline-research/16940192.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "42c07dd0bbacfc1ff44f78d6ce69810a58946e53c76bf5d3bf8385db5278ba8b", "start_char": 0, "end_char": 1942, "text_sha256": "42c07dd0bbacfc1ff44f78d6ce69810a58946e53c76bf5d3bf8385db5278ba8b"} [citrulline-p16940192] 5-methyltetrahydrofolate rapidly improves endothelial function and decreases superoxide production in human vessels: effects on vascular tetrahydrobiopterin availability and endothelial nitric oxide synthase coupling. (2006). https://pubmed.ncbi.nlm.nih.gov/16940192/ DOI: 10.1161/circulationaha.106.612325

evidence_span

{"source_cache": "artifacts/citrulline-research/16940192.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "42c07dd0bbacfc1ff44f78d6ce69810a58946e53c76bf5d3bf8385db5278ba8b", "start_char": 0, "end_char": 1942, "text_sha256": "42c07dd0bbacfc1ff44f78d6ce69810a58946e53c76bf5d3bf8385db5278ba8b"}

experimental_model

Ex-vivo vessel exposure and randomized pre-harvest infusion

exposure

5-MTHF ex vivo 1-100 micromolar; intravenous 5-MTHF or placebo in a separate subset

limitations

Uses 5-MTHF and acute vessel endpoints; cannot be generalized to all folic-acid doses or combination supplements.

nutrient_topic

Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline

organism

Human, vessels from 117 CABG patients

plain_language

The experiment distinguished this effect from simply lowering homocysteine.

primary_references

[citrulline-p16940192] 5-methyltetrahydrofolate rapidly improves endothelial function and decreases superoxide production in human vessels: effects on vascular tetrahydrobiopterin availability and endothelial nitric oxide synthase coupling. (2006). https://pubmed.ncbi.nlm.nih.gov/16940192/ DOI: 10.1161/circulationaha.106.612325

tissue_or_cell_type

Saphenous veins and internal mammary arteries

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 762–773

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Ex-vivo vessel exposure and randomized pre-harvest infusion · source_derived_draft · unverified_draft

### citrulline-folate-superoxide 5-MTHF reduced vascular superoxide; the effect was not explained by direct superoxide scavenging or changed plasma homocysteine. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: The experiment distinguished this effect from simply lowering homocysteine. organism: Human, vessels from 117 CABG patients tissue_or_cell_type: Saphenous veins and internal mammary arteries experimental_model: Ex-vivo vessel exposure and randomized pre-harvest infusion limitations: Uses 5-MTHF and acute vessel endpoints; cannot be generalized to all folic-acid doses or combination supplements. exposure: 5-MTHF ex vivo 1-100 micromolar; intravenous 5-MTHF or placebo in a separate subset evidence_span: {"source_cache": "artifacts/citrulline-research/16940192.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "42c07dd0bbacfc1ff44f78d6ce69810a58946e53c76bf5d3bf8385db5278ba8b", "start_char": 0, "end_char": 1942, "text_sha256": "42c07dd0bbacfc1ff44f78d6ce69810a58946e53c76bf5d3bf8385db5278ba8b"} [citrulline-p16940192] 5-methyltetrahydrofolate rapidly improves endothelial function and decreases superoxide production in human vessels: effects on vascular tetrahydrobiopterin availability and endothelial nitric oxide synthase coupling. (2006). https://pubmed.ncbi.nlm.nih.gov/16940192/ DOI: 10.1161/circulationaha.106.612325

evidence_span

{"source_cache": "artifacts/citrulline-research/10608822.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd", "start_char": 0, "end_char": 2100, "text_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd"}

experimental_model

Purified recombinant enzyme activity and cofactor analysis

exposure

Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements

limitations

Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people.

nutrient_topic

Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline

organism

Human NOS3 expressed in yeast

plain_language

Supplying substrate does not replace the required pterin cofactor.

primary_references

[citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658

tissue_or_cell_type

Endothelial NOS enzyme preparation

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 515–526

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant enzyme activity and cofactor analysis · source_derived_draft · unverified_draft

### citrulline-nos-bh4 Purified human eNOS showed an absolute BH4 requirement for the measured catalytic reaction. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: Supplying substrate does not replace the required pterin cofactor. organism: Human NOS3 expressed in yeast tissue_or_cell_type: Endothelial NOS enzyme preparation experimental_model: Purified recombinant enzyme activity and cofactor analysis limitations: Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people. exposure: Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements evidence_span: {"source_cache": "artifacts/citrulline-research/10608822.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd", "start_char": 0, "end_char": 2100, "text_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd"} [citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658

evidence_span

{"source_cache": "artifacts/citrulline-research/10608822.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd", "start_char": 0, "end_char": 2100, "text_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd"}

experimental_model

Purified recombinant enzyme activity and cofactor analysis

exposure

Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements

limitations

Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people.

nutrient_topic

Citrulline research collection; topical membership is not evidence of a direct dietary effect. · L-Citrulline

organism

Human NOS3 expressed in yeast

plain_language

Cofactor and substrate helped stabilize the paired enzyme structure.

primary_references

[citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658

tissue_or_cell_type

Endothelial NOS enzyme preparation

Citrulline: arginine recycling, nitrogen disposal and nutrient connections (2026-09-17) · lines 580–591

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant enzyme activity and cofactor analysis · source_derived_draft · unverified_draft

### citrulline-nos-dimer BH4 plus arginine shifted human eNOS toward dimers during low-temperature electrophoresis. Condition category: normal nutrient_topic: Citrulline research collection; topical membership is not evidence of a direct dietary effect. plain_language: Cofactor and substrate helped stabilize the paired enzyme structure. organism: Human NOS3 expressed in yeast tissue_or_cell_type: Endothelial NOS enzyme preparation experimental_model: Purified recombinant enzyme activity and cofactor analysis limitations: Biochemical cofactor findings do not show that extra dietary cofactors increase NO in healthy people. exposure: Arginine substrate; BH4, FAD, FMN, heme, iron and zinc measurements evidence_span: {"source_cache": "artifacts/citrulline-research/10608822.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd", "start_char": 0, "end_char": 2100, "text_sha256": "1600b193cc63f30b204285729710bb81f34bc2918a8ca7f97aa97bc4acd998fd"} [citrulline-p10608822] Characterization of recombinant human endothelial nitric-oxide synthase purified from the yeast Pichia pastoris. (1999). https://pubmed.ncbi.nlm.nih.gov/10608822/ DOI: 10.1074/jbc.274.53.37658